1. Field of the Invention
The present invention relates to a hot air blower, and more particularly, to a hot air blower including a pressure regulation valve for adjusting an air pressure supplied into a burner of the hot air blower at an appropriate pressure.
2. Description of the Prior Art
In general, hot air blowers are used to provide hot air into a closed space such as a plant or remove moisture from a green house such as a vinyl house, a cow house, and so on.
The hot air blowers may be classified into an electric heat exchange type of applying electricity to a heater or a hot-wire coil to heat sucked air to a high temperature and then discharging the hot air to the exterior using the blower, or a combustion heating type of combusting fuel in a combustion chamber to heat air and discharge the heated air using a blowing fan.
FIGS. 1 and 2 show a typical example of the combustion heating type hot air blower, among the hot air blowers.
The combustion heating type hot air blower includes a blower body 10 having a fuel tank 12 disposed at its lower part a combustion chamber 20 disposed in front of the blower body 10 and over the fuel tank 12, a burner assembly 22 having an injection nozzle 22a installed at a rear part of the combustion chamber 20 to inject fuel and an ignition plug 22b for igniting the fuel, a vane pump 28 connected to the burner assembly 22 via a fuel supply line 24 and generating a predetermined pressure to supply fuel, a blower fan 32 for blowing air into the combustion chamber 20, and a drive motor 30 for rotating the blower fan 32.
The vane pump 28 is merely an example of an air compression pump, and other kinds of air compression pumps may be installed in the blower.
In addition, the blower includes a controller (not shown) for controlling the entire operation, a pair of wheels 14 installed at a lower end of the blower body 10 to enable movement of the blower, a stopper 16 installed opposite to the wheels 14, and a handle 18 installed at an upper part of the blower body 10.
Further, as shown in FIGS. 3A and 3B, the blower includes a pressure regulation valve 40 installed at one side of the vane pump 28 to supply introduced air through an air suction port 10a at an appropriate pressure. The pressure regulation valve 40 is positioned on a path through which the compressed air generated by the vane pump 28 moves to the burner assembly 22.
The pressure regulation valve 40 adjusts a supply pressure of the air compressed by the vane pump 28 to supply the air into the injection nozzle 22a of the burner assembly 22 at an appropriate pressure.
Hereinafter, the above constitution will be described in detail.
First, the vane pump 28 includes a rotor 35 rotated by the drive motor 30, a front housing 28d installed at one side of the rotor 35, and a rear housing 28e installed opposite to the front housing 28d. The rotor 35 constitutes a compression part of the vane pump 28.
In addition, a chamber 37 in which air flows is formed between the front housing 28d and the rear housing 28e. 
Further, the front housing 28d and the rear housing 28e have separation projections 28f and 28g projecting from their inner surfaces toward each other, respectively. The separation projections 28f and 28g are adhered to each other via a gasket 28h to divide the chamber 37 into an introduction chamber 37a and a compression chamber 37b. 
Furthermore, the rear housing 28e has the air suction port 10a in communication with the introduction chamber 37a. 
The introduction chamber 37a includes a filter 36 for filtering foreign substances included in the air passing therethrough.
In addition, as shown in FIG. 3B, an introduction hole 28a is formed in the front housing 28d corresponding to the introduction chamber 37a to introduce the air passed through the filter 36 into the rotor 35.
Further, a discharge hole 28b is formed in the front housing 28d corresponding to the compression chamber 37b to discharge the air compressed by the rotor 35 to the compression chamber 37b. 
The compression chamber 37b also has a filter 38 to filter foreign substances included in the compressed air discharged through the discharge hole 28b. 
An air line 28c is formed around the compression chamber 37b to convey the compressed air to the burner assembly 22.
In addition, the pressure regulation valve (or a relief valve) 40 is installed at the rear housing 28e to lower the pressure of the compressed air discharged from the vane pump 28. The pressure regulation valve 40 is installed in a hole 42 formed in the rear housing 28e so that the compressed air is discharged through the hole 42.
The air in the compression chamber 37b lowered to a predetermined value by the pressure regulation valve 40 is conveyed to the burner assembly 22 through the air line 28c. 
A partition wall 28j is formed in the compression chamber 37b to divide the chamber 37b into a space in which the air line 28c is formed and a space in which the pressure regulation valve 40 is installed. A relatively small through-hole 39 is formed in the partition wall 28j. Therefore, it is possible to prevent the air of pressure higher than the predetermined value from being discharged through the air line 28c. 
In addition, a pressure gauge and a plug 41 are installed at the rear housing 28e adjacent to the through-hole 39 to close a pressure gauge port for measuring the pressure of the compressed air.
The pressure regulation valve 40 is installed in the hole 42, and includes a ball 43, a spring 44, and a pressure regulation screw 45.
Therefore, when the pressure regulation screw 45 is tightened, the spring 44 is compressed to prevent displacement even at a high pressure. When the pressure regulation screw 45 is loosened, the spring 44 is released to cause displacement even at a lower pressure.
Hereinafter, a process of reducing the pressure of the air compressed by the vane pump 28 using the pressure regulation valve 40 and supplying the air into the injection nozzle 22a will be described.
The exterior air introduced into the air suction port 10a is introduced into the rotor 35 of the vane pump 28 via the filter 36 in the introduction chamber 37a and the introduction hole 28a, and the air compressed by the rotor 35 is discharged through the discharge hole 28b to move to the compression chamber 37b via the air filter 38.
As described above, the compressed air moved into the compression chamber 37b passes through the through-hole 39 and then moves to the air line 28c to be supplied into the injection nozzle 22a of the burner assembly 22.
A manufacturer can adjust the pressure of the air discharged from the vane pump 28 using the pressure regulation valve 40 to supply the air into the injection nozzle 22a at a uniform pressure.
In addition, the compressed air supplied into the injection nozzle 22a moves along the air line 28c to suck fuel in the fuel tank 12 to supply the fuel into the injection nozzle 22a. When the air pressure is high, the amount of the sucked fuel is increased, and when the air pressure is low, the amount of the sucked fuel is reduced.
Therefore, when the compressed air is supplied into the injection nozzle 22a at a high pressure, a heating value is raised, and when the compressed air is supplied at a low pressure, a heating value is lowered.
That is, the pressure of the compressed air discharged from the vane pump 28 is different according to the hot air blower. For example, when the pressure regulation valve 40 is set to be opened at 7 psi, even when the pressure of the compressed air supplied into the injection nozzle 22a of the burner assembly 22 is higher than 7 psi, the compressed air is supplied into the injection nozzle 22a at the pressure of 7 psi.
For example, when the pressure of the compressed air discharged from the vane pump 28 installed in the hot air blower is 10 psi, the pressure regulation valve 40 is opened to reduce the pressure of the compressed air in the compression chamber 37b to 7 psi and then supply the compressed air to the injection nozzle 22a. Even when the pressure of the compressed air discharged from the vane pump 28 installed at another hot air blower is 9 psi, the pressure regulation valve 40 reduces the pressure to 7 psi and then supplies the compressed air to the injection nozzle 22a. 
As described above, since the conventional hot air blower is set to a fixed pressure by the manufacturers, it is difficult for a user to adjust the pressure of the compressed air according to necessities.
That is, since the conventional hot air blower includes a single pressure regulation valve set to a certain discharge pressure, it is difficult for a user to adjust the pressure of the compressed supplied to the burner assembly.
As a result, when it is needed to reduce a heating value of the conventional hot air blower, operation of the hot air blower must be stopped.
In addition, in order to adjust the heating value generated in the combustion chamber, an expensive two-stage electronic pump may be installed instead of the vane pump. However, in this case, manufacturing cost of the hot air blower is increased, and installation of the two-stage electronic pump complicates the structure of the hot air blower.